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MOUNT(8)                  BSD System Manager's Manual                 MOUNT(8)

NAME
     mount -- mount file systems

SYNOPSIS
     mount [-Aadfruvw] [-t type]
     mount [-dfruvw] special | node
     mount [-dfruvw] [-o options] [-t type] special node

DESCRIPTION
     The mount command invokes a filesystem-specific program to prepare and
     graft the special device or remote node (rhost:path) on to the file sys-
     tem tree at the point node.

     If either special or node are not provided, the appropriate information
     is taken from the fstab(5) file.  The provided argument is looked up
     first in the ``fs_file'', then in the ``fs_spec'' column.  If the match-
     ing entry in fstab(5) has the string ``from_mount'' as its ``fs_spec''
     field, the device or remote file system already mounted at the location
     specified by ``fs_spec'' will be used.

     If both special and node are given, the disklabel is checked for the
     filesystem type.

     In NetBSD, a file system can only be mounted by an ordinary user who owns
     the point node and has access to the special device (at least read per-
     missions).  In addition, the vfs.generic.usermount sysctl(3) must be set
     to 1 to permit file system mounting by ordinary users.  See also
     sysctl(8).

     The system maintains a list of currently mounted file systems.  If no
     arguments are given to mount, this list is printed.

     The options are as follows:

     -A      Causes mount to try to mount all of the file systems listed in
             the fstab(5) file except those for which the ``noauto'' option is
             specified.

     -a      Similar to the -A flag, except that if a file system (other than
             the root file system) appears to be already mounted, mount will
             not try to mount it again.  mount assumes that a file system is
             already mounted if a file system with the same type is mounted on
             the given mount point.  More stringent checks are not possible
             because some file system types report strange values for the
             mounted-from device for mounted file systems.

     -d      Causes everything to be done except for the invocation of the
             filesystem-specific program.  This option is useful in conjunc-
             tion with the -v flag to determine what the mount command is try-
             ing to do.

     -f      Forces the revocation of write access when trying to downgrade a
             filesystem mount status from read-write to read-only.

     -o      Options are specified with a -o flag followed by a comma sepa-
             rated string of options.  The following options are available:

             async       All I/O to the file system should be done asyn-
                         chronously.  In the event of a crash, it is
                         impossible for the system to verify the integrity of
                         data on a file system mounted with this option.  You
                         should only use this option if you have an applica-
                         tion-specific data recovery mechanism, or are willing
                         to recreate the file system from scratch.

             noasync     Clear async mode.

             force       The same as -f; forces the revocation of write access
                         when trying to downgrade a filesystem mount status
                         from read-write to read-only.

             getargs     Retrieves the filesystem specific mount arguments for
                         the given mounted filesystem and prints them.

             noatime     Never update the access time field for files.  This
                         option is useful for optimizing read performance on
                         filesystems that are used as news spools.

             noauto      This filesystem should be skipped when mount is run
                         with the -a flag.

             nodev       Do not interpret character or block special devices
                         on the file system.  This option is useful for a
                         server that has file systems containing special
                         devices for architectures other than its own.

             nodevmtime  Do not update modification times on device special
                         files.  This option is useful on laptops or other
                         systems that perform power management.

             nocoredump  Do not allow programs to create crash dumps (core
                         files) on the file system.  This option can be used
                         to help protect sensitive data by keeping core files
                         (which may contain sensitive data) from being created
                         on insecure file systems.  Only core files that would
                         be created by program crashes are prevented by use of
                         this flag; the behavior of savecore(8) is not
                         affected.

             noexec      Do not allow execution of any binaries on the mounted
                         file system.  This option is useful for a server that
                         has file systems containing binaries for architec-
                         tures other than its own.

             hidden      By setting the MNT_IGNORE flag, causes the mount
                         point to be excluded from the list of filesystems
                         shown by default with df(1).

             nosuid      Do not allow set-user-identifier or set-group-identi-
                         fier bits to take effect.

             rdonly      The same as -r; mount the file system read-only (even
                         the super-user may not write it).

             softdep     (FFS only) Mount the filesystem using soft-dependen-
                         cies.  This means that metadata will not be written
                         immediately, but is written in an ordered fashion to
                         keep the on-disk state of the filesystem consistent.
                         This results in significant speedups for file cre-
                         ate/delete operations.  This option will be ignored
                         when using the -u flag and a filesystem is already
                         mounted read/write.  This option has gone through
                         moderate to heavy testing, but should still be used
                         with care.  It requires the SOFTDEP option to be
                         enabled in the running kernel.

             symperm     Recognize permission of symbolic link when reading or
                         traversing link.

             sync        All I/O to the file system should be done syn-
                         chronously.  This is not equivalent to the normal
                         mode in which only metadata is written synchronously.

             nosync      Clear sync mode.

             update      The same as -u; indicate that the status of an
                         already mounted file system should be changed.

             union       Causes the namespace at the mount point to appear as
                         the union of the mounted filesystem root and the
                         existing directory.  Lookups will be done in the
                         mounted filesystem first.  If those operations fail
                         due to a non-existent file the underlying directory
                         is then accessed.  All creates are done in the
                         mounted filesystem, except for the fdesc file system.

             Any additional options specific to a given filesystem type (see
             the -t option) may be passed as a comma separated list; these
             options are distinguished by a leading ``-'' (dash).  Options
             that take a value are specified using the syntax -option=value.
             For example, the mount command:

                   mount -t mfs -o nosuid,-N,-s=32m swap /tmp

             causes mount to execute the equivalent of:

                   /sbin/mount_mfs -o nosuid -N -s 32m swap /tmp

     -r      The file system is to be mounted read-only.  Mount the file sys-
             tem read-only (even the super-user may not write it).  The same
             as the ``rdonly'' argument to the -o option.

     -t type
             The argument following the -t is used to indicate the file system
             type.  The type ffs is the default.  The -t option can be used to
             indicate that the actions should only be taken on filesystems of
             the specified type.  More than one type may be specified in a
             comma separated list.  The list of filesystem types can be pre-
             fixed with ``no'' to specify the filesystem types for which
             action should not be taken.  For example, the mount command:

                   mount -a -t nonfs,mfs

             mounts all filesystems except those of type NFS and MFS.

             mount will attempt to execute a program in /sbin/mount_XXX where
             XXX is replaced by the type name.  For example, nfs filesystems
             are mounted by the program /sbin/mount_nfs.

     -u      The -u flag indicates that the status of an already mounted file
             system should be changed.  Any of the options discussed above
             (the -o option) may be changed; also a file system can be changed
             from read-only to read-write or vice versa.  An attempt to change
             from read-write to read-only will fail if any files on the
             filesystem are currently open for writing unless the -f flag is
             also specified.  The set of options is determined by first
             extracting the options for the file system from the fstab(5)
             file, then applying any options specified by the -o argument, and
             finally applying the -r or -w option.

     -v      Verbose mode.  If this flag is specified more than once, then the
             filesystem-specific mount arguments are printed for the given
             mounted filesystem.

     -w      The file system object is to be read and write.

     The options specific to the various file system types are described in
     the manual pages for those file systems' mount_XXX commands.  For
     instance the options specific to Berkeley Fast File System (FFS) are
     described in the mount_ffs(8) manual page.

     The particular type of filesystem in each partition of a disk can be
     found by examining the disk label with the disklabel(8) command.

FILES
     /etc/fstab  file system table

EXAMPLES
     Some useful examples:

           CD-ROM
                   mount -t cd9660 -r /dev/cd0a /cdrom

           MS-DOS
                   mount -t msdos /dev/fd0a /floppy

           NFS
                   mount nfs-server-host:/directory/path /mount-point

           MFS (32 megabyte)
                   mount -t mfs -o nosuid,-s=32m swap /tmp

     The "noauto" directive in /etc/fstab can be used to make it easy to manu-
     ally mount and unmount removable media using just the mountpoint file-
     name, with an entry like this:

           /dev/cd0a /cdrom cd9660 ro,noauto 0 0

     That would allow a simple command like "mount /cdrom" or "umount /cdrom"
     for media using the ISO-9660 filesystem format in the first CD-ROM drive.

SEE ALSO
     df(1), mount(2), fstab(5), disklabel(8), mount_ados(8), mount_cd9660(8),
     mount_ext2fs(8), mount_fdesc(8), mount_ffs(8), mount_filecore(8),
     mount_kernfs(8), mount_lfs(8), mount_mfs(8), mount_msdos(8),
     mount_nfs(8), mount_ntfs(8), mount_null(8), mount_overlay(8),
     mount_portal(8), mount_procfs(8), mount_umap(8), mount_union(8),
     umount(8)

HISTORY
     A mount command appeared in Version 6 AT&T UNIX.

BSD                             March 27, 2004                             BSD